Just click on the films, for streaming video directly online (approx 30s loading time).
You can also download most of these .wmv files from TV ISG.
Also check out some wicked motor bike trials video games, free stuff online.

Also check out the excellent crash videos compiled by t33zr
(all the auch!! series to download at the bottom of the page).
That will give you some ideas of how things can go horribly wrong, including some nasty chain or handlebar failures.